Large Biomolecules

All Organisms Contain the Same Four Classes of Large Biomolecules lipids - hydrophobic =>macromolecules - chains of subunits polysaccharides - repetitive macromolecules =>information macromolecules proteins nucleic acids

constituents of hydrated and dry organisms Figure 3.2

All Organisms Contain the Same Four Classes of Large Biomolecules large biomolecules consist of the same subunits in all organisms large biomolecules are assembled, fresh from their subunits, by each organism

similar reactions assemble and disassemble all classes of large biomolecules Figure 3.3

Table 3.1

Four Classes of Large Biomolecules Lipids –defined by hydrophobicity –chemically diverse hydrocarbons –several functions, e.g. energy storage - fats & oils cell structures - membranes regulation - steroid & other hormones insulation - electrical & thermal

Four Classes of Large Biomolecules Lipids –triglycerides fats solid at 20˚C; oils liquid at 20˚C energy per gram > carbohydrates or proteins

triglyceride synthesis (esterification) Figure 3.18

fats, oils, cis, trans Figure 3.19 saturated unsaturated

Four Classes of Large Biomolecules membrane lipids –phospholipids diglycerides + polar head group amphipathic

a membrane phospholipid Figure 3.20

biomembrane segment Figure 5.2

amphipathic membrane phospholipids Figure 3.21

Four Classes of Large Biomolecules other lipid classes - carotenoids (isoprenoids) Figure 3.22 CH 3 H 2 C = C – C = CH 2 H

Four Classes of Large Biomolecules other lipid classes - steroids (isoprenoids) Figure 3.23 CH 3 H 2 C = C – C = CH 2 H

Four Classes of Large Biomolecules other lipid classes - vitamins –Vitamin E –Vitamin K

Four Classes of Large Biomolecules other lipid classes - waxes –high molecular weight, hydrophobic compounds –useful for waterproofing p. 54

Four Classes of Large Biomolecules carbohydrates: sugars & their polymers –monosaccharides - subunits of polymers trioses, tetroses, pentoses, hexoses, etc. –families of structural & optical isomers aldoses; ketoses monosaccharides ≥5 C’s occur in 3 forms modified monosaccharides play important roles

a triose and two pentoses Figure 3.14

three hexoses Figure aldoses and a ketose

three forms of glucose Figure 3.13  anomers ~1% ~99%

modified monosaccharides and a polysaccharide Figure 3.17

Four Classes of Large Biomolecules carbohydrates: sugars & their polymers –monosaccharides - subunits of polymers –disaccharides two monosaccharides linked by a specific glycosidic bond –differ by subunits & linked carbons

two glucose-glucose disaccharides Figure 3.15

Four Classes of Large Biomolecules carbohydrates: sugars & their polymers –monosaccharides - subunits of polymers –disaccharides –oligosaccharides 3-20 monosaccharides linked by glycosidic bonds

Four Classes of Large Biomolecules carbohydrates: sugars & their polymers –monosaccharides - subunits of polymers –disaccharides –oligosaccharides –polysaccharides thousands of monosaccharides linked by glycosidic bonds

 -1,4 polyglucose Figure 3.16

 -1,4 polyglucose with  -1,6 branche Figure 3.16

three forms of polyglucose Figure 3.16

Four Classes of Large Biomolecules proteins: polymers of amino acid subunits –widely diverse functions structure, protection, transport, defense, regulation, movement, catalysis –thousands of unique structures some bind prosthetic groups –enzymes are chemical catalysts functions are defined by 3-D shape

Four Classes of Large Biomolecules proteins: polymers of amino acid subunits –twenty kinds of (protein) amino acids –four levels of structure primary - sequence of amino acids –amino (N) terminus & carboxy (C) terminus

amino acids share a common structure but have different R groups H H 2 N - C - COOH R amine carboxylic acid variable

Amino acids organized by R groups Figure 3.2

cysteines can form disulfide bridges Figure 3.4

peptide bonds join the carboxyl group to the amino group long chains are called polypeptides Figure 3.5

4. Quaternary Structure: Polypeptides assemble into larger molecules Figure Tertiary Structure: Polypeptides fold 2. Secondary Structure: a.  Helix 1. Primary Structure: Polypeptide chain b.  Pleated sheet Figure 3.6 The Four Levels of Protein Structure

Four Classes of Large Biomolecules proteins: polymers of amino acid subunits tertiary & quaternary structures are stabilized by several interactions H-bonds - between polar R groups ionic interactions - between charged R groups hydrophobic interactions - between non-polar R groups disulfide bridges - between cysteines

interactions that stabilize 3-D structures Figure 3.9

Four Classes of Large Biomolecules proteins: polymers of amino acid subunits –3-D folding is assisted by molecular chaperones during formation following denaturation

protein denaturation Figure 3.11

chaperones assist in folding polypeptides Figure 3.12

Four Classes of Large Biomolecules nucleic acids: polymers of nucleotide subunits –DNA (deoxyribonucleic acid), & RNA (ribonucleic acid) –Store (DNA), transmit (DNA) & express (RNA) hereditary information –The Central Dogma of Molecular Biology Information Flow DNA=>RNA=>polypeptide

Four Classes of Large Biomolecules nucleic acids: polymers of nucleotide subunits –nucleotide components pentose sugar nitrogenous bases –purines: adenine, guanine –pyrimidines: cyosine, thymine, uracil phosphate group O - O=P-O- O -

5-carbon sugars: pentoses Figure 3.13

5 bases Figure 3.24

nucleotide components Figure 3.24

Four Classes of Large Biomolecules nucleic acids: polymers of nucleotide subunits –nucleotides linked by phosphodiester bonds –sugar-phosphate backbone

Hydrogen bonds between purines and pyrimidines hold the two strands of DNA together. Figure 3.25 Figure 3.25 Distinguishing Characteristics of DNA and RNA

DNA double helix Figure 3.27

double- stranded segments in a single- stranded RNA Figure 3.26